Eon takes on a challenge: opening Space Engine for the very first time. He picks it over Universe Sandbox because it has better graphics, and right away the screen warns it's in an "alpha state, work in progress." That's an honest label software makers use — alpha means the program is still being built. Before Eon can fly anywhere, he has to do something every gamer secretly hates and every smart person does anyway: read the tutorial. "Let me learn the tutorial," he says, "because I have no idea how this works." That turns out to be the best part.

Learning the words for what's on the screen

The tutorial doesn't just teach buttons — it teaches vocabulary, and Eon's dad makes sure he can name each thing:

  • Interface — "the thing we use to interact with the game." Everything you click is part of the interface.
  • Toolbar — "a bar but full of tools." Space Engine has one on every edge: a main toolbar (left), a navigation toolbar (bottom-left, for movement and time), a camera toolbar (bottom-right, for brightness and zoom), and a filter toolbar (right, to hide or show things).
  • Hover — resting your mouse on an icon without clicking to see a hint. Eon keeps clicking by accident; "Hover means you just hover and see," his dad repeats.
  • Hotkey — a keyboard shortcut that jumps straight to a tool.
  • Selection pointer — the tiny rotating arrows that show which object you've clicked on.

He also learns to drag: hold the mouse button down and then move, which lets him spin a planet around in the wiki window. Small skills, but they're the controls behind everything that follows.

Earth, by the numbers

When the tutorial selects Earth, a panel of real data pops up — and Eon already knows some of it. He spots the ESI (Earth Similarity Index) reading 1.00. "One is exactly the same, because it is the Earth!" Exactly right: ESI compares any world to ours, and Earth scores a perfect 1.

The panel keeps going, and each number means something real:

  • Gravity: 1 g. "If you jump, it'll be like this" — normal, because 1 g is the pull we feel every day.
  • Composition: H₂O, N₂, O₂. Water, nitrogen, and oxygen — the air you're breathing and the oceans you swim in.

This is the heart of the lesson: a game window full of numbers is really a window full of facts about a real place. Eon even uses the filter toolbar to switch those facts off one at a time — hide the clouds to see the surface, hide the water, hide the atmosphere — to see what Earth would be without each layer.

Real objects vs. "procedural" ones

Clicking the wiki tool, Eon learns Space Engine labels every object as either a real object or a procedural one. He guesses the word before his dad finishes: "Procedurally generated!" That's the big idea — the program stores thousands of real stars and planets from astronomy, then has the computer invent billions of billions more to fill the unexplored parts of the universe. The label tells you which is which.

All the way to a black hole

Now the fun. Eon flies to Saturn, tilts the view to catch its rings, then sets a far bigger target: TON 618, one of the largest black holes known. At first it's just darkness — "we're already here but we can't see anything" — because a black hole gives off no light. Turning down the exposure and switching to realistic mode reveals a glowing, spinning disk. The data is staggering: a diameter of nearly 20 light-years for the whole system.

Then his dad explains why it's spitting out two bright beams: it's a quasar. The black hole is pulling in so much gas that it can't swallow it all, so the leftover matter gets blasted back out in two jets, top and bottom. Eon connects it to the movie Interstellar and asks a genuinely good scientist's question: why did that black hole have no jets, but this one does? His dad's honest answer — "I don't know" — is a reminder that real space is still full of mysteries. They learn TON 618 isn't even the record-holder; an even bigger one, Phoenix A, has to be manually generated because it isn't built into the game yet.

They finish with a size-comparison chart of the solar system: Earth tiny beside the massive Sun — yet from the ground the Sun looks small, "because it's really far away." Scale, again, is the whole point.

Try it

Open any space app or map of the solar system and find Earth. Write down three numbers about it — its gravity, what its air is made of, and how big it is compared to the Sun — just like Eon read off the screen. Then pick a faraway object (Saturn, a star, a black hole) and zoom out until Earth disappears completely. The time it takes for Earth to vanish is the size of space.